1. Field of the Invention
This invention relates to self-adjusting chucks, whether for hand-held tools or machine tools.
2. Prior Art
Time taken in changing "bits" due to adjusting and tightening chucks, on hand-held power tools in particular, can be compounded with lost chuck keys and even injury if the drill or tool is accidentally started before the chuck key is removed.
Keyless chucks are known but they suffer from an anomaly in that either they cannot be tightened sufficiently by hand or they take a longer time to be adjusted than a chuck employing a chuck key.
In the case of known chucks there is often a need to re-tighten the chuck during use due to the work-torque which is applied to the jaws causing vibrations to be transmitted directly to the jaw-clamping threads, resulting in the chuck loosening.
The term "bit" is intended to include other tools besides drill bits which are required to be held in a chuck.